Planet Linux Australia

So my Nitrokey HSM arrived and it works great, thanks to the Nitrokey peeps for sending me one.

Because the OpenSC PKCS #11 module is a little more lightweight than some of the other vendors, which often implement mechanisms that are not actually supported by the hardware (e.g. the Opencryptoki TPM module), I wrote up some documentation on how to use the device, focusing on how to extract the public keys for using outside of PKCS #11, as the Nitrokey doesn’t implement any of the public key functions.

This also encouraged me to add a whole bunch more of the import/extraction functions for the diverse key formats, including getting very frustrated at the lack of documentation for little things like how OpenSSL stores EC public keys (the answer is as SubjectPublicKeyInfo from X.509), although I think there might be some operating system specific glitches with encoding some DER structures. I think I need to move from pyasn1 to asn1crypto.

Ah, the comfortable cat! Most people agree that cats are experts at being comfortable and getting the best out of life, with the assistance of their human friends – but how did this come about? Geneticists and historians are continuing to study how cats and people came to live together and how cats came to […]

Develop a higher quality mode in the 2000 to 3000 bit/s range, that can be used on HF channels with modest SNRs (around 10dB)

I ran some numbers on the new OFDM modem and LDPC codes, and turns out we can get 3000 bit/s of codec data through a 2000 Hz channel at down to 7dB SNR.

Now 3000 bit/s is broadband for me – I’ve spent years being very frugal with my bits while I play in low SNR HF land. However it’s still a bit low for Opus which kicks in at 6000 bit/s. I can’t squeeze 6000 bit/s through a 2000 Hz RF channel without higher order QAM constellations which means SNRs approaching 20dB.

So – what can I do with 3000 bit/s and Codec 2? I decided to try wideband(-ish) audio – the sort of audio bandwidth you get from Skype or AM broadcast radio. So I spent a few weeks modifying Codec 2 to work at 16 kHz sample rate, and Jean Marc gave me a few tips on using DCTs to code the bits.

Sample (2) is as good as Codec 2 can do, its the unquantised model parameters (harmonic phases and amplitudes). It’s all down hill from here as we quantise or toss away parameters.

In (3) I’m using a one bit voicing model, this is very vocoder and shouldn’t work this well. MBE/MELP all say you need mixed excitation. Exploring that conundrum would be a good Masters degree topic.

In (3) I can hear the pitch estimator making a few mistakes, e.g. around “sheet” on the female.

The extra 4kHz of audio bandwidth doesn’t take many more bits to encode, as the ear has a log frequency response. It’s maybe 20% more bits than 4kHz audio.

You can hear some words like “well” are muddy and indistinct in the 1800 bit/s sample (4). This usually means the formants (spectral) peaks are not well defined, so we might be tossing away a little too much information.

The clipping on the SSB sample (5) around the words “depth” and “hours” is an artifact of the PathSim AGC. But dat noise. It gets really fatiguing after a while.

Wideband audio is a big paradigm shift for Push To Talk (PTT) radio. You can’t do this with analog radio: 2000 Hz of RF bandwidth, 8000 Hz of audio bandwidth. I’m not aware of any wideband PTT radio systems – they all work at best 4000 Hz audio bandwidth. DVSI has a wideband codec, but at a much higher bit rate (8000 bits/s).

Current wideband codecs shoot for artifact-free speech (and indeed general audio signals like music). Codec 2 wideband will still have noticeable artifacts, and probably won’t like music. Big question is will end users prefer this over SSB, or say analog FM – at the same SNR? What will 8kHz audio sound like on your HT?

We shall see. I need to spend some time cleaning up the algorithms, chasing down a few bugs, and getting it all into C, but I plan to be testing over the air later this year.

This artefact is made of stone. It measures about 12 x 8 x 3 cm. It fits easily and comfortably into an adult’s hand. The surface of the stone is mostly smooth and rounded, it looks a little like a river cobble. However, one side – the right-hand side in the photo above – is shaped so that 2 smooth sides meet in a straight, sharpish edge. Such formations do not occur on naturally rounded stones, which tells us that this was shaped by people and not just rounded in a river. The smoothed edges meeting in a sharp edge tell us that this is ground-stone technology. Ground stone technology is a technique used by people to create smooth, sharp edges on stones. People grind the stone against other rocks, occasionally using sand and water to facilitate the process, usually in a single direction. This forms a smooth surface which ends in a sharp edge.

Neolithic Axe

Ground stone technology is usually associated with the Neolithic period in Europe and Asia. In the northern hemisphere, this technology was primarily used by people who were learning to domesticate plants and animals. These early farmers learned to grind grains, such as wheat and barley, between two stones to make flour – thus breaking down the structure of the plant and making it easier to digest. Our modern mortar and pestle is a descendant of this process. Early farmers would have noticed that these actions produced smooth and sharp edges on the stones. These observations would have led them to apply this technique to other tools which they used and thus develop the ground-stone technology. Here (picture on right) we can see an Egyptian ground stone axe from the Neolithic period. The toolmaker has chosen an attractive red and white stone to make this axe-head.

In Japan this technology is much older than elsewhere in the northern hemisphere, and ground-stone axes have been found dating to 30,000 years ago during the Japanese Palaeolithic period. Until recently these were thought to be the oldest examples of ground-stone technology in the world. However, in 2016, Australian archaeologists Peter Hiscock, Sue O’Connor, Jane Balme and Tim Maloney reported in an article in the journal Australian Archaeology, the finding of a tiny flake of stone (just over 1 cm long and 1/2 cm wide) from a ground stone axe in layers dated to 44,000 to 49,000 years ago at the site of Carpenter’s Gap in the Kimberley region of north-west Australia. This tiny flake of stone – easily missed by anyone not paying close attention – is an excellent example of the extreme importance of ‘archaeological context’. Archaeological material that remains in its original context (known as in situ) can be dated accurately and associated with other material from the same layers, thus allowing us to understand more about the material. Anything removed from the context usually can not be dated and only very limited information can be learnt.

The find from the Kimberley makes Australia the oldest place in the world to have ground-stone technology. The tiny chip of stone, broken off a larger ground-stone artefact, probably an axe, was made by the ancestors of Aboriginal people in the millennia after they arrived on this continent. These early Australians did not practise agriculture, but they did eat various grains, which they leaned to grind between stones to make flour. It is possible that whilst processing these grains they learned to grind stone tools as well. Our artefact, shown above, is undated. It was found, totally removed from its original context, stored under an old house in Brisbane. The artefact is useful as a teaching aid, allowing students to touch and hold a ground-stone axe made by Aboriginal people in Australia’s past. However, since it was removed from its original context at some point, we do not know how old it is, or even where it came from exactly.

Our artefact is a stone tool. Specifically, it is a ground stone axe, made using technology that dates back almost 50,000 years in Australia! These axes were usually made by rubbing a hard stone cobble against rocks by the side of a creek. Water from the creek was used as a lubricant, and often sand was added as an extra abrasive. The making of ground-stone axes often left long grooves in these rocks. These are called ‘grinding grooves’ and can still be found near some creeks in the landscape today, such as in Kuringai Chase National Park in Sydney. The ground-stone axes were usually hafted using sticks and lashings of plant fibre, to produce a tool that could be used for cutting vegetation or other uses. Other stone tools look different to the one shown above, especially those made by flaking stone; however, smooth stones should always be carefully examined in case they are also ground-stone artefacts and not just simple stones!

Andrew Pam will be demonstrating a range of video games that run natively on Linux and explicitly include programming skills as part of the game including SpaceChem, InfiniFactory, TIS-100, Shenzen I/O, Else Heart.Break(), Hack 'n' Slash and Human Resource Machine. He will seek feedback on the suitability of these games for teaching programming skills to non-programmers and the possibility of group play in a classroom or workshop setting.

After using Duolingo for over a year and accumulating almost 100,000 points I thought it would do the right thing and pay for the Plus service. It was exactly the right time as I would be travelling overseas and the ability to do lessons offline and have them sync later seemed ideal.

For the first few days it seemed to be operating fine; I had downloaded the German tree and was working my way through it. Then I downloaded the French tree, and several problems started to emerge.

tl;dr: I’ve recently moved to the San Francisco Bay Area, received my US Work Authorization, so now I’m looking for somewhere to work. I have a résumé and an e-mail address!

I’ve worked a lot in Free and Open Source Software communities over the last five years, both in Australia and overseas. While much of my focus has been on the Python community, I’ve also worked more broadly in the Open Source world. I’ve been doing this community work entirely as a volunteer, most of the time working in full-time software engineering jobs which haven’t related to my work in the Open Source world.

It’s pretty clear that I want to move into a job where I can use the skills I’ve been volunteering for the last few years, and put them to good use both for my company, and for the communities I serve.

What I’m interested in doing fits best into a developer advocacy or community management sort of role. Working full-time on helping people in tech be better at what they do would be just wonderful. That said, my background is in code, and working in software engineering with a like-minded company would also be pretty exciting (better still if I get to write a lot of Python).

Something with a strong developer relations element. I enjoy working with other developers, and I love having the opportunity to get them excited about things that I’m excited about. As a conference organiser, I’m very aware of the line between terrible marketing shilling, and genuine advocacy by and for developers: I want to help whoever I work for end up on the right side of that line.

Either in San Francisco, North of San Francisco, or Remote-Friendly. I live in Petaluma, a lovely town about 50 minutes north of San Francisco, with my wonderful partner, Josh. We’re pretty happy up here, but I’m happy to regularly commute as far as San Francisco. I’ll consider opportunities in other cities, but they’d need to primarily be remote.

Relevant to Open Source. The Open Source world is where my experience is, it’s where I know people, and it’s the world where I can be most credible. This doesn’t mean I need to be working on open source itself, but I’d love to be able to show up at OSCON or linux.conf.au and be excited to have my company’s name on my badge.

Why would I be good at this? I’ve been working on building and interacting with communities of developers, especially in the Free and Open Source Software world, for the last five years.

You can find a complete list of what I’ve done in my résumé, but here’s a selection of what I think’s notable:

Co-organised two editions of PyCon Australia, and led the linux.conf.au 2017 team. I’ve led PyCon AU, from inception, to bidding, to the successful execution for two years in a row. As the public face of PyCon AU, I made sure that the conference had the right people interested in speaking, and that we had many from Australian Python community interested in attending. I took what I learned at PyCon AU and applied it to run linux.conf.au 2017, where our CFP attracted its largest ever response (beating the previous record by more than 30%).

Developed Registrasion, an open source conference ticket system. I designed and developed a ticket sales system that allowed for automation of the most significant time sinks that linux.conf.au and PyCon Australia registration staff had experienced in previous years. Registrasion was Open Sourced, and several other conferences are considering adopting it.

Given talks at countless open source and developer events, both in Australia, and overseas. I’ve presented at OSCON, PyCons in five countries, and myriad other conferences. I’ve presented on a whole lot of technical topics, and I’ve recently started talking more about the community-level projects I’ve been involved with.

Designed, ran, and grew PyCon Australia’s outreach and inclusion programmes. Each year, PyCon Australia has offered upwards of $10,000 (around 10% of conference budget) in grants to people who otherwise wouldn’t be able to attend the conference: this is not just speakers, but people whose presence would improve the conference just by being there. I’ve led a team to assess applications for these grants, and lead our outreach efforts to make sure we find the right people to receive these grants.

Served as a council member for Linux Australia. Linux Australia is the peak body for Open Source communities in Australia, as well as underwriting the region’s more popular Open Source and Developer conferences. In particular, I led a project to design governance policies to help make sure the conferences we underwrite are properly budgeted and planned.

OK, so you’ve got the core work covered for the term and now you have all those reports to write and admin to catch up on. Well, the OpenSTEM™ Understanding Our World® HASS plus Science material has heaps of activities which help students to practise core curricular skills and can keep students occupied. Here are some ideas:

Aunt Madge is a perennial favourite with students of all ages. In this activity, students use clues to follow Aunt Madge around the world trying to return her forgotten suitcase. There’s a wide range of locations to choose from on every continent – both natural and constructed places. This activity can be tailored for group work, or the whole class, and by adjusting the number of locations to be found, the teacher can adjust to the available time, anywhere from 10-15 minutes to a whole lesson. Younger students enjoy matching the pictures of locations and trying to find the countries on the map. Older students can find out further information about the locations on the information sheets. Teachers can even choose a theme for the locations (such as “Ancient History” or “Aboriginal Places”) and see if students can guess what it is.

Students in Years 3 to 6 have undertaken the Ancient Sailing Ships activity this term, however, there is a vast scope for additional aspects to this activity. Have students compared the performance of square-rigged versus lateen sails? How about varying the number of masts? Have students raced the vessels against each other? (a water trough and a fan is all that’s needed for some exciting races) Teachers can encourage the students to examine the effects of other changes to ship design, such as adding a keel or any other innovations students can come up with, which can be tested. Perhaps classes or grades can even race their ships against each other.

Students in years 5 and 6 in particular enjoy the Trade and Barter activity, which teaches them the basics of Economics without them even realising it! This activity covers so many different aspects of the curriculum, that it is always a good one to revisit, even though it was not in this term’s units. Students enjoy the challenge and will find the activity different each time. It is a particularly good choice for a large chunk of time, or for smaller groups; perhaps a more experienced group can coach other students. The section of the activity which has students developing their own system of writing is one that lends itself to extension and can even be spun off as a separate activity.

Students of all ages enjoy many of the games listed in the resource Games From The Past. Several of these games are best done whilst running around outside, so if that is an option, then choose from the Aboriginal, Chinese or Zulu games. Many of these games can be played by large groups. Older students might like to try recreating some of the rules for some of the games of Ancient Egypt or the Aztecs. If this resource wasn’t part of the resources for your particular unit, it can be downloaded from the OpenSTEM™ site directly.

Class Discussions

The b) and c) sections of the Teacher Handbooks contain suggestions for topics of discussion – such as Women Explorers or global citizenship, or ideas for drawings that the students can do. These can also be undertaken as additional activities. Teachers could divide students into groups to research and explore particular aspects of these topics, or stage debates, allowing students to practise persuasive writing skills as well.

Adding events to a timeline, or the class calendar, also good ways to practise core skills.

The OpenSTEM™ Our World map is used as the perfect complement to many of the Understanding Our World® units. This map comes blank and country names are added to the map during activities. The end of term is also a good chance for students to continue adding country names to the map. These can be cut out of the resource World Countries, which supplies the names in a suitable font size. Students can use the resource World Maps to match the country names to their locations.

The OpenSTEM™ Understanding Our World® units have only 9 weeks per term, so this is the last week! Our youngest students are looking at some Aboriginal Places; slightly older older students are thinking about what their school and local area were like when their parents and grandparents were children; and students in years 3 to 6 are completing their presentations and anything else that might be outstanding from the term.

Foundation/Prep/Kindy

Students in the stand-alone Foundation/Prep/Kindy class (Unit F.2) examine Aboriginal Places this week. Students examine which places are special to Aboriginal people, and how these places should be cared for by Aboriginal people and the broader community. Several of the Australian places in the Aunt Madge’s Suitcase Activity can be used to support this discussion in the classroom. Students in an integrated Foundation/Prep/Kindy and Year 1 class (Unit F.6), as well as Year 1 (Unit 1.2), 2 (Unit 2.2) and 3 (Unit 3.2) students consider life in the times of their parents and grandparents, with specific reference to their school, or the local area studied during this unit. Teachers may wish to invite older members of the community (including interested parents and/or grandparents) in to the class to describe their memories of the area in former years. Were any of them past students of the school? This is a great opportunity for students to come up with their own questions about life in past times.

Years 3 to 6
Aunt Madge

Students in Year 3 (Unit 3.6), 4 (Unit 4.2), 5 (Unit 5.2) and 6 (Unit 6.2) are finishing off their presentations and any outstanding work this week. Sometimes the middle of term can be very rushed and so it’s always good to have some breathing space at the end to catch up on anything that might have been squeezed out before. For those classes where everyone is up-to-date and looking for extra activities, the Aunt Madge’s Suitcase Activity is always popular with students and can be used to support their learning. Teachers may wish to select a range of destinations appropriate to the work covered during the term and encourage students to think about how those destinations relate to the material covered in class. Destinations may be selected by continent or theme – e.g. natural places or historical sites. A further advantage of Aunt Madge is that the activity can be tailored to fit the available time – from 5 or 10 minutes for a single destination, to 45 minutes or more for a full selection; and played in groups, or as a whole class, allowing some students to undertake the activity while other students may be catching up on other work. Students may also wish to revisit aspects of the Ancient Sailing Ships Activity and expand on their investigations.

Although this is the last week of this term’s units, we will have some more suggestions for extra activities next week – particularly those that keep the students busy while teachers attend to marking or compiling of reports.

Debian Linux version 9 (codename "Stretch") is scheduled for release on 17 June 2017. Join us in celebrating the release and assisting anyone who would like to install or upgrade to the new version!

There will also be the usual casual hands-on workshop, Linux installation, configuration and assistance and advice. Bring your laptop if you need help with a particular issue. This will now occur BEFORE the talks from 12:30 to 14:00. The talks will commence at 14:00 (2pm) so there is time for people to have lunch nearby.

Gaussian is a well-known computational chemistry package, and sometimes subject to debate over its license (e.g., the terms state researchers who develop competing software packages are not permitted to use the software, compare performance etc). Whilst I have some strong opinions about such a license, this will be elaborated at another time. The purpose here is to illustrate the use of heredocs with Slurm.